Restoring Hydraulic Function to California's Grasslands Through Vegetation Management.

Vegetation cover influences the near-surface hydrology of landscapes.  The introduction of annual grasses to California's perennial grasslands not only changed the look of the landscape but resulted in a change in the hydrologic dynamics of these areas.  Shallow rooted annual grasses do not facilitate the rapid transmission of water deep into the soil profile as perennial grasses do.  The objective of this study was to quantify the difference in surface saturated hydraulic conductivity between a range of soils under both annual and perennial grass.  Our results indicate that soils with perennial grasses have a greater saturated hydraulic conductivity (~80 %) compared to corresponding soils with annual grasses.  Our results indicate that managing California's grasslands for perennial grasses would alter the hydrologic dynamics of the landscape, resulting in lower peak flood flows and greater shallow aquifer recharge.  This benefit should be calculated into management decisions.